1. Field of the Invention
The invention relates in general to an indoor UHF antenna device for a digital television, and more particularly to a flat antenna device, which can be set conveniently without occupying too much space and is easy to be adjusted to different angles to receive wireless digital television signals of polarized waves from different directions.
2. Description of the Related Art
Referring to FIG. 8, a conventional digital antenna 50 for receiving digital television signals is shown. The digital antenna 50 includes a base 51 and a rod body 53 supported by the base 51. The rod body 53 is a telescopic antenna. When using the digital antenna 50, the base 51 is connected with an earth terminal of a television cable (not shown in the diagram), and the rod body 53 is connected to a signal input terminal of the television cable.
According to FIG. 8, it is clear that the digital antenna receives wireless signals in a direction perpendicular to the level. However, a conventional digital television transmitter generally includes horizontal polarized waves and vertical polarized waves. If it is desired to receive all kinds of optimal wireless signals from different transmitters, the receiving angle of the antenna requires appropriate adjustment. Take the antenna structure of FIG. 8 for example; the antenna can receive clear signals of the vertical polarized waves. If it is desired to receive clear signals of the horizontal polarized waves, the whole antenna must be put horizontal. Nevertheless, this kind of antenna is quite bulky and lacks a design for easy adjustment of the reception angles. Thereby the conventional antenna is not suitable to be adjusted to appropriate angles for receiving the signals.
Referring to FIG. 9, a structure diagram of a UHF indoor antenna 60 is shown. The UHF indoor antenna 60 mainly includes a baseboard 61, a substantially triangular antenna 62 with two ends, and a coaxial cable 63. Both ends of the triangular antenna 62 inset into the baseboard 61, and also are connected with an earth terminal and signal terminal (not shown in the diagram) of the coaxial cable 63. Comparing the UHF antenna 60 with the above-mentioned rod antenna 50, the size of the UHF antenna 60 is smaller, which is more convenient to be placed indoors. However, the triangular antenna 62 has to be connected perpendicularly with the baseboard 61, so that the size of the UHF antenna 60 cannot be further reduced. Therefore, the conventional indoor antennas still require further improving.